1. Field of the Invention
The present invention is concerned with an improved conveyor-type modular heat exchange apparatus especially designed for use in commercial scale plants employing the methods described in U.S. Pat. No. 4,088,562. More particularly, it is concerned with such apparatus which includes a heat exchange zone formed of easily replaced and/or repaired, restricted-throat interconnected modules, and an improved shale-supporting endless conveyor which is oriented such that two oppositely moving stretches thereof pass through the heat exchange zone and respectively support hot spent shale and raw shale, so as to preheat the latter prior to full processing thereof.
2. Description of the Prior Art
U.S. Pat. No. 4,088,562 represents a major breakthrough in the art of hydrocarbon recovery from oil shale. As disclosed in that patent, raw, incoming shale to the process is preheated in a heat exchange zone or tunnel, using the hot, spent oil shale from the process.
It will of course be appreciated that use of the hot, spent shale as a source of heat for the raw, incoming shale greatly lowers the total heat input for the process and improves the overall energy efficiency thereof. However, in order to be truly effective, an efficient heat exchange device must be provided. A prime difficulty in this connection is that, on a commercial scale, extremely large quantities of shale must be routinely handled. Thus, the exchanger apparatus must be extremely strong and durable. At the same time, in order to avoid costly down times, the apparatus should be susceptible to quick and easy repair and/or replacement.
As an adjunct to the foregoing, it is also of course necessary to convey the raw shale from a mine or other pickup site, and to correspondingly convey the spent shale to a disposal area. The conveyor device used in this connection must likewise be of simple, durable construction, in order to meet the dictates of commercial operation.
Prior heat exchanger and conveyor devices are illustrated in U.S. Pat. Nos. 2,218,935, 2,157,321, 1,992,704, 2,411,179, 3,431,657, 2,775,823, 614,847, 449,464, 3,339,712, and 1,374,874.